1. Technical Field
The present invention relates to a backlight, and more particularly, the present invention relates to a backlight unit and a display apparatus having the backlight unit.
2. Description of the Related Art
In general, a liquid crystal display panel uses a backlight unit including one or more light sources to provide illumination for the display, which is not self-emissive. Examples of suitable light sources include a cold cathode fluorescent lamp, a light emitting diode, etc.
Particularly, in a direct-illumination type backlight unit in which the light sources are arranged behind the liquid crystal display, an upper portion of the backlight unit is in a relatively high temperature and a lower portion of the backlight unit is in a relatively lower temperature due to a convection phenomenon. The cold cathode fluorescent lamp used as the light source of the backlight unit has a negative resistance characteristic with respect to a temperature, and thus an impedance of the cold cathode fluorescent lamp decreases when the temperature increases. Additionally, the impedance of the cold cathode fluorescent lamp increases when the temperature decreases. Accordingly, although the same voltage is applied to the light sources, relatively large current flows through the light sources arranged on the upper portion while the light sources are driven in parallel. This uneven current may then lead to uneven backlighting where some portions of the liquid crystal display appear brighter than other portions.